Sunday, February 25, 2007
My CMG 2006 paper on virtualization was recently blogged at HP Labs in the context of hyperthreading being considered harmful to processor performance. The paper actually provides a general unified framework in which to understand hyperthreading, hypervisors (e.g., VMware, and Xen), and hyperservices (e.g., P2P virtual networks like
BitTorrent); the latter being an outgrowth of something I wrote in response to an online analysis of Gnutella.
The VM-spectrum concept is based on my observations that: (i) disparate types of virtual machines lie on a discrete spectrum bounded by hyperthreading at one extreme and hyperservices at the other, and (ii) poll-based scheduling is the common architectural element in most VM implementations. The associated polling frequency (from GHz to μHz) positions each VM into a region of the VM-spectrum. Several case studies are analyzed to illustrate how this framework could make VMs more visible to performance management tools.